Content Delivery Performance Analysis of a Cache-Enabled UAV Base Station Assisted Cellular Network for Metaverse Users

Metaverse can provide powerful human-centric interactive experiences for users and metaverse application content is the fundamental component that supports the metaverse. Considering that metaverse users are more sensitive to the delay of content delivery service, unmanned aerial vehicles (UAV) can be used as aerial base stations (BSs) to assist a cellular network to provide better content delivery service for delay-sensitive metaverse users as UAV base stations (UBSs) have big potential for line-of-sight (LoS) transmission and can be deployed closer to metaverse users than macro base stations (MBSs). This paper studies the content delivery performance analysis of a cache-enabled UBS-assisted cellular network for metaverse users. Analytical models are derived for investigating the content delivery performance of the network in terms of the content delivery success probability of the network and the average content delivery delay of a metaverse user. In deriving the analytical models, a more realistic repulsive point process is considered for modeling the location distribution of MBSs, and an air-to-ground (A2G) channel model with both a LoS link and a non-line-of-sight (NLoS) link is considered. Moreover, the cache hit probability of a UBS using a probabilistic caching strategy is also taken into consideration. A BS association strategy for delay-sensitive metaverse users based on the strongest average received power at a user and the cache hit probability of a UBS is proposed. In addition, the association probabilities with the association strategy are derived for different types of base stations. A lower bound of the content delivery success probability and an upper bound of the average content delivery delay are obtained based on the derived analytical models. The numerical results justify the effectiveness and advantage of the proposed BS association strategy and show that there exist an optimal UBS height and an optimal value of the number of UBSs, which result in the optimal content delivery performance. The obtained results can provide theoretical guidance for the deployment of UBSs in a cache-enabled UBS-assisted cellular network to provide better human-centric content delivery service for metaverse user.